1. Field of the Invention
The present invention relates to a power converter. More particularly, the present invention relates to a voltage regulator.
2. Description of Related Art
FIG. 1 shows a traditional voltage regulator for supplying a regulated voltage VZ from a line voltage VAC. A rectifier circuit 10 including a plurality of rectifiers is coupled to the line voltage VAC and provides the rectification to generate an input voltage VIN. A capacitor 11 is connected from the input voltage VIN to a capacitor 15 to produce the regulated voltage VZ. A zener diode 16 is connected to the capacitor 15 for the regulation. A resistor 12 is used for the discharge of the capacitor 11. This traditional voltage regulator has been widely used in home appliances, such as coffee maker, cooling fan and remote controller, etc. However, the drawback of this traditional voltage regulator is high power consumption, particularly for light load and no load situations. Both the resistor 12 and the zener diode 16 cause significant power losses. Therefore, reducing the power loss is required. The object of present invention is to provide a high efficiency voltage regulator for generating a regulated voltage from an AC power source.